Oxidation haircoloring products have dominated the world market over the past 50 years as the preferred method of changing the color of gray or pigmented hair for both men and women. These products are also referred to as “permanent haircolors”, as they permanently alter the hair's coloration. Reapplication occurs as the hair's new growth becomes noticeable. Oxidation hair dyes are normally sold in the form of a two-component kit. In one container is an alkaline composition that contains oxidative dyes and an appropriate vehicle. In the other container is a developer composition that utilizes an oxidizing agent, usually hydrogen peroxide. The two compositions are mixed immediately prior to use and applied to the hair. The alkaline pH of the mixture causes the hair shaft to swell, allowing the dye precursors to penetrate into the cortex of the hair. These dye precursors are then oxidized, which combine to form larger molecules. These larger molecules contain a significant level of resonance, hence producing a colored product that is visible from the exterior of the hair. After an appropriate development time, the mixture is rinsed from the hair. The color of the hair is then permanently altered. Depending upon the pH of the mixture and strength of the developer, these systems can have the capability to lighten the hair's natural pigment, or only deposit color without the lightening action. The actual time that the mixed haircolorant is on the hair varies widely depending upon the product and desired affect, although it is generally 5 to 45 minutes before rinsing occurs. As the development time is a necessity, the viscosity of the mixture and its Theological properties are of significant importance to the product's overall performance.
The most common product form for oxidation haircolor products is to have both the dye and developer components as flowable liquids. That way the dye portion can be easily poured into an oversized developer bottle containing the oxidizer, and quickly mixed with moderate agitation. The consistency of the resulting mixture and the formulas that comprise these systems are of considerable importance to haircolor manufacturers. Traditional dye/developer systems relied upon tint phases with low levels of water and insoluble surfactants dissolved in organic solvents. Typically these formulas would have less than 30% water. The developers would be simple solutions of water and 3 to 12% hydrogen peroxide. As the two solutions are mixed, the high water content in the developer would precipitate out the water insoluble surfactants. With careful selection of surfactants for the tint phase, this precipitate would be in the form of a gel. The net result would yield a flowable gel mixture with thixotropic rheological features to allow for easy dispensing from a narrow applicator tip, while producing acceptable stay-put properties after application to the hair.
These types of systems were considered ideal for two component haircolorants, and have undergone little change since their inception. One improvement is taught in U.S. Pat. No. 6,187,058, where the volatile organic solvents are replaced with non-volatile materials, allowing for more environmentally friendly products to be marketed. A major departure from the low water haircolor systems evolved as a particular type of water insoluble anionic polymer was developed in the 1980's. First marketed as Acrysol ICS, and later under the Aculyn trademark by Rohm & Haas, Acrylates/Steareth-20 Methylacrylate Copolymer was found to be stable in hydrogen peroxide and form a thin, liquid dispersion in such systems. Today there are a host of similar materials that are commercially produced and can be described as; polymers of an ester of a fatty carboxylic acid and a polyalkylene glycol ether of a fatty alcohol and two or more monomers of fatty carboxylic acids or their esters.
For simplicity sake these can be referred to as water insoluble Acrylate Copolymers. Once these developers which are formulated with the specified copolymers come in contact with an alkaline solution, the entire mixture will thicken by polymer neutralization and solubilization. This allowed for the development of the so-called “high aqueous” dye phase of haircoloring products. These inventions simplified the formulation of this portion of the haircolor components. Typically they contain 50% or more water, a limited quantity of surfactants and organic solvents, along with dye intermediates and antioxidants. The first invention to describe this technology was in Re. 33,786, where the Acrysol ICS was the only compound mentioned. Since this time, modifications to polymers and composition attributes have been developed. These include the addition of various conditioning compounds as described in U.S. Pat. Nos. 5,376,146 and 5,393,305. U.S. Pat. No. 6,660,045 teaches the preparation of a creme using an acrylates copolymer in the developer, although with the large number of ingredients listed in the formulations this invention has lost its high aqueous nature. In general, these types of hair color systems have worked well, although the rheology produced by the acrylates copolymers alone is more Newtonian in nature, and tends to run off the hair. In practice, these systems have to be modified with the addition of other thickeners to produce a thixotropic product. This will rendered these formulas less efficient. Other Polymers of similar utility but are water soluble, most notably homo and copolymers of acylic acid crosslinked with a polyalkenyl polyether sold under the Carbopol brand by Noveon Corp. can be used in similar fashion, but lack the peroxide stability necessary for shelf life of finished products.
The object of this invention is to provide alternate formulations and manufacturing methods to achieve a high aqueous haircolor system suitable for use with any conceivable type of oxidation colorant. These formulations use known cosmetic ingredients in unique combinations which produce unexpected thickening properties upon mixing of both system components. There are additional advantages over traditional thickening systems and previously invented high aqueous products. These improvements over existing technology include: 1) Ease of formulation and manufacture, 2) Lower cost of ingredients, 3) More efficient dying system (less dyes required), 4) Improved gray coverage of finished products, 5) Superior theological benefits without the need for additional surfactants, 6) Safer for consumers and the environment, with no monomers present as with formulations that contain Aculyn.